The present invention relates generally to wheel suspension systems for motor vehicles, and more particularly, to an integrated rear wheel suspension system.
A suspension system on an automobile works with the tires, frame or unit body, wheels, wheel bearings, brake system, and steering system to provide a safe and comfortable mode of transportation. A suspension system has several important functions, including supporting the various components of an automobile, allowing the tires to move up and down to provide a comfortable ride, allowing for rapid cornering without extreme body roll, keeping the tires on the road surface, preventing excessive body squat when accelerating, preventing excessive body dive when braking, allowing the front wheels to turn side-to-side for steering, and, in combination with the steering system, keeping the wheels in correct alignment.
These suspension systems use front and rear springs to suspend a vehicle""s frame, body or unitized body, engine, and powertrain above the wheels. These relatively heavy assemblies constitute what is known as xe2x80x9csprungxe2x80x9d weight. The xe2x80x9cunsprungxe2x80x9d weight, on the other hand, includes wheels and tires, brake assemblies, and other structural members not supported by the springs. Unfortunately, high xe2x80x9cunsprungxe2x80x9d weight may result in adverse vehicle characteristics. Reduction of xe2x80x9cunsprungxe2x80x9d weight, therefore, is desirable.
Many front and rear suspension systems incorporate compression type coil springs. Some front and rear coil springs are mounted between a lower control arm and spring housing or seat in the vehicle frame or body. Coil springs are made of steel or steel alloy and may have evenly or variably spaced coils to provide adequate durability and vehicle stability under all intended load conditions. Unfortunately, compression type coil springs are typically heavy and require significant packaging space within the vehicle.
When coil springs are used in a front or rear suspensions, three or four linkages are typically placed between the wheel axles and the frame. These linkages support driving and braking torque, the vertical load due to road loads, and cornering (lateral) loads. The lower control arms pivot in the frame members and sometimes support the rear coil springs to provide for up and down movement of the axle and wheel assembly. Unfortunately, these linkages increase the amount of xe2x80x9cunsprungxe2x80x9d weight, while increasing overall part count and complexity.
In addition, an anti-roll bar is usually attached from the rear suspension lower control arm to the frame side rail to prevent side sway (roll motion) of the body. Unfortunately, anti-roll bars are typically heavy and require significant packaging space within a vehicle. In addition, anti-roll bars increase the overall part count and complexity of suspension systems.
The disadvantages associated with these conventional rear suspension techniques have made it apparent that a new technique for rear suspension is needed. The new technique should integrate multiple automotive suspension functions into one integral unit. Additionally, the new technique should reduce part count and weight while potentially improving noise, vibration and harshness (NVH) and reducing complexity. The present invention is directed to these ends.
It is, therefore, an object of the invention to provide an improved and reliable integrated rear wheel suspension system. Another object of the invention is to reduce part count, system weight, and system complexity, while potentially improving NVH.
In accordance with the objects of this invention, an integrated rear wheel suspension system is provided. In one embodiment of the invention, a rear wheel suspension system replaces the lower control arms, upper control arms, coil springs, and anti-roll bar assembly in the prior art with a composite member. By carefully designing the shape of the beam, the material system and the pivot locations, the ride and roll rates (stiffness) and camber and toe characteristics of the original prior art suspension system can be preserved.
The present invention thus achieves an improved integrated rear wheel suspension system. The present invention is advantageous in that it integrates multiple automotive suspension functions into one integral unit.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by the number of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.